#include <iostream>
using namespace std;

class Account {
    private:
        int balance;
        static int roi;
    public:
        void setBalance(int b) {
            balance = b;
        }
        static void setROI(int r) {
            roi = r;
        }
        static void printROI() {
            cout << roi << endl;
        }
};

int Account::roi = 5;

int main() {
    Account a1;
    a1.setBalance(500);
    Account::printROI();
    Account::setROI(7);
    Account::printROI();
}